20 - 30 minutos
Old battery would randomly die, even if it said it was at 100%. On average it lasted about 20 minutes.
The surgery went perfectly! The only hard part was getting that stupid "Do not remove" sticker off, because it's so hard to fit anything but the spudger in there, so you can't just peel it off with your fingers. Also, the ribbon cable is different than some of the other ones I've seen. The ones I've seen slide BACK to unlock, but these ones on the iPhone display actually flip UP. I pulled it out accidentally while it was still locked and had a little bit of a hassle getting it back in until I realized that I hadn't unlocked it in the first place. Everything worked fine though once I got it all back together and the battery now lasts for almost 2 days!
See the above about the "Do not remove" sticker and the display ribbon cable.